Most Apple computers, including the iMac, use slot-loading disc drives. Rather than using a sliding tray, a slot-loading drive pulls the disc through a thin slot on the computer case. These drives are only meant for standard size CDs and DVDs. Using a mini CD with a slot-loading drive can cause real problems. There are many iMac users who have ended up with a jammed drive due to a mini CD. You will need some additional equipment to use a mini CD with your iMac. There are two different ways of going about this task. Writer Bio

How to Put Mini CDs Into an iMac - 23